Bar code reader with an integrated scanning component module mountable on printed circuit board

ABSTRACT

A bar code reader has an integrated scanning component module which is mountable on a printed circuit board. In one embodiment, the module may include the digitizer/decoder electronics, enabling the module to be used with a generic PCB. In some embodiments, the module includes a high speed optical scanning arrangement having an optical element which extends longitudinally of a flexible member, secured at one end. In other embodiments, the invention extends to a hand-held optical scanner having a scanning assembly, detector and data transmission coupling all mounted to a common printed circuit board, preferably located within a manually-graspable handle. In yet a further embodiment, an abuse-detector or accelerometer is provided for determining when the device is exposed to deceleration above a predetermined limit, and optionally for automatically shutting down applications programs and for providing a black-box-record of a short time frame before the device was exposed to an unexpected shock. Preferably, the reader is shock protected by a thermo-plastic elastomer housing section. An outgoing light beam is directed at a non-orthogonal angle relative to the PCB.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. Ser. No. 09/045,427, filed Mar.20, 1998, now allowed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a high-speed scanningarrangement, and particularly although not exclusively to such ascanning arrangement for use in hand-held or fixed optical scanners suchas bar code scanners. In one embodiment the invention relates to a barcode reader with an integrated scanning component module mountable on aprinted circuit board.

2. Description of the Related Art

Various optical readers and optical scanners have been developedheretofore to optically read bar code symbols applied to objects inorder to identify the object by optically reading the symbol thereon.The bar code symbol itself is a coded pattern comprised of a series ofbars of various widths and spaced apart from one another to bound spacesof various widths, the bars and spaces having different light reflectingproperties. The readers and scanners electro-optically decoded the codedpatterns to multiple digit representations descriptive of the objects.Scanners of this general type have been disclosed, for example, in U.S.Pat. Nos. 4,251,798; 4,360,798; 4,369,361; 4,387,297; 4,593,186;4,496,831; 4,409,470; 4,808,804; 4,816,661; 4,816,660; and 4,871,904,all of said patents having been assigned to the same assignee as theinstant invention and being hereby incorporated herein by reference.

As disclosed in the above-identified patents and applications, aparticularly advantageous embodiment of such a scanner resided, interalia, in emitting a light beam, preferably a laser beam, emitted from alight source, preferably a gas laser or a laser diode, and in directingthe laser beam to a symbol to be read. En route to the symbol, the laserbeam was directed to, and reflected off, a light reflector of a scanningcomponent. The scanning component moved the reflector in a cyclicalfashion and caused the laser beam to repetitively scan the symbol. Thesymbol reflected the laser beam incident thereon. A portion of theincident light reflected off the symbol was collected and detected by adetector component, e.g. a photodiode, of the scanner. The photodiodehad a field of view, and the detected light over the field of view wasdecoded by electrical decode circuitry into data desciprive of thesymbol for subsequent processing. The cyclically movable reflector sweptthe laser beam across the symbol and/or swept the field of view duringscanning.

U.S. Pat. Nos. 4,387,297 and 4,496,831 disclose a high speed scanningcomponent including an electric motor operative for reciprocatinglyoscillating a reflector in opposite circumferential directions relativeto an output shaft of the motor. Electrical power is continuouslyapplied to the motor during scanning. The light beam which impinges onthe light reflector is rapidly swept across a symbol to be scanned in apredetermined cyclical manner. The scanning component comprises at leastone scan means for sweeping the symbol along a predetermined direction(X-axis) lengthwise thereof. The scanning component may also compriseanother scan means for sweeping the symbol along a transverse direction(Y-axis) which is substantially orthogonal to the predetermineddirection, to thereby generate a raster-type scan pattern over thesymbol. In addition to a single scan line and the raster-type pattern,other types of scan patterns are also possible, such as, x-shaped,Lissajous, curvilinear (see U.S. Pat. No. 4,871,904), etc. For example,if the X and Y axis scanning motors are both driven such that the lightreflectors are driven at a sinusoidally-varying rate of speed, then thescan pattern at the reference plant will be a Lissajous-type pattern foromni-directional scanning of the symbols. The use of two separatescanning motors and control means to produce the multi-axis andomni-directional scanning pattern increases material and labor costs aswell as the amount of electrical power needed to operate the scanner. Inaddition, the relatively complicated motor shaft and bearingarrangements of the scanning components may result in a useful life thatis inadequate for some applications.

European patent application 456,095 also discloses various prior arttypes of high speed scanning arrangements, as do U.S. Pat. Nos.5,280,165 and 5,367,151.

SUMMARY OF THE INVENTION Objects of the Invention

It is a general object of the present invention to enhance thestate-the-art of high speed scanning arrangements, and particularlyalthough not exclusively for such arrangements for use in opticalscanners for reading indicia of differing light reflectivity,particularly laser scanners for reading bar code symbols.

A further object of the present invention is to provide an inexpensive,robust and easily replaceable scanning arrangement

Yet another object of the invention is to increase the working lifetimeof the scanning components.

Yet another object is to provide a robust, low cost, hand-held opticalscanner.

Yet a further object is to provide a means for determining when ascanner has been exposed to high levels of mechanical shock.

Yet a further object is to attempt to alleviate high levels ofmechanical shock.

Features of the Invention

According to one aspect of the invention, there is provided an opticalscanning assembly including an optics module having an optical scannerand an optical detector for detecting light reflected from an indiciabeing read and for providing data signals representative thereof, and aprinted circuit board (PCB) carrying electrical circuitry forcontrolling said optics module. A first electrical connector jointlymovable with the optics module mates with a second electrical connectorfixed to the PCB for electrically coupling the optics module and thePCB.

The electrical connectors may supply both power and control signals tothe optics module, and may also operate to transfer the data signalsfrom the optics module to the PCB. The electrical connection isconveniently of the plug-in type (for example, it maybePCMCIA-compatible). In preferred embodiments, the electrical connectorsact to mount the optics module on the PCB. Alternatively, the module maybe otherwise secured to the PCB, with the electrical connectors actingsimply to transfer power and/or data.

According to a further aspect of the present invention, there isprovided a hand-held electronic device including an abuse-detector fordetermining when said device has been exposed to mechanical shock abovea predetermined design limit.

The abuse-detector may conveniently be secured, for example by means ofan adhesive, to a PCB of the electronic device. Preferred electronicdevices include all types of portable and/or hand-held electronicequipment, including portable computer terminals, data entry devices,bar code readers, digital cameras and so on.

According to yet a further aspect of the present invention there isprovided a hand-held electronic device including an accelerometer fordetermining when said device is exposed to acceleration above apredetermined limit and for producing a signal representative thereof,and a CPU for running an applications program, said CPU being arrangedto shut down said applications program and to store related statusinformation when said signal is received from said accelerometer.

The invention further extends to a method of determining when ahand-held electronic device is exposed to acceleration above apredetermined limit. Such a method preferably includes the step ofproducing a signal representative thereof, and closing down any activeapplications programs and storing related status information.

When it is determined that the device is being exposed to anacceleration above a predetermined limit, the CPU may enter a power-downmode. In addition, one or more mechanical protection devices may operateto prevent mechanical damage from the expected resultant shock. Forexample, mechanical protection may be applied, by means of a mechanicallock, shock absorbers, or the like, to prevent mechanical damage to theheads and/or platters of a disk drive.

In yet a further aspect of the invention there is provided a hand-heldelectronic device including an accelerometer having an accelerometeroutput, a deceleration-level detector for determining from saidaccelerometer output when said device has been exposed to a decelerationabove a given value, and a store for storing for later analysis valuesrepresentative of the accelerometer output for a time period prior tothe deceleration-level detector determining that the device has been soexposed.

In yet another aspect there is provided a method of operating ahand-held electronic device, said device including an accelerometerhaving an accelerometer output and a store, the method comprising:

(a) Monitoring said accelerometer output, and determining when saiddevice has been exposed to a deceleration greater than a given value;and

(b) Storing in the store, for later analysis, values representative ofthe accelerometer output for a time period prior to the saiddetermination.

Preferably, the accelerometer output is filtered or smoothed, beforebeing applied to the deceleration-level detector. Means may then beprovided, for example, a signal comparator, for determining when thedeceleration level is sufficiently high. Once such a determination hasbeen made, the prior output of the accelerometer (for example over thepreceding five or ten seconds) is stored in memory for future analysis.Conveniently, an A/D converter is also provided, sampling the signal atsufficiently frequent intervals that future analysis may be carried outon the discrete digitized and stored values.

Separate x, y and z accelerometers may be provided, supplyingrespectively acceleration outputs in the x, y and z directions. Eachoutput may be separately filtered and compared with a given accelerationlevel, thereby allowing separate triggering in each of the x, y and zchannels. In addition, a separate channel may be provided for otherstatus information, such as for example temperature information, on/offstatus information for the electronic device and so on. A further storemay be provided for storing such information in the event that adeceleration is detected of a fixed limit.

The invention may be carried into practice in a number of ways andseveral specific embodiments will now be described, by way of example,with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a perspective view of a hand-held optical scanner, suitablefor use with the scanning arrangement of the present invention;

FIG. 1b is a perspective view of a hand-held data-entry/scanningterminal suitable for use with the scanning arrangement of the presentinvention;

FIGS. 2a and 2 b show an embodiment of a scanning arrangement accordingto the present invention;

FIG. 3 shows another embodiment;

FIGS. 4a and 4 b are top and side views, respectively, of an alternativelow-cost hand-held scanner;

FIGS. 5a and 5 b are, respectively, views from above and to the side ofthe scanning mechanism for use in the embodiment of FIGS. 4a and 4 b;

FIG. 6 shows an exemplary PCMCIA card connector, for use with any of thepreceding embodiments;

FIG. 7 shows, schematically, an abuse detector for portable electronicequipment;

FIG. 8 is a longitudinal cross-section through the detector of FIG. 7;

FIGS. 9 to 11 are flow diagrams illustrating a method of shockpreparation in portable electronic equipment;

FIG. 12 is a partial section through an optics module according to afurther embodiment of the invention;

FIG. 13 is a partial view from above of the module of FIG. 12;

FIG. 14 is a partial view from one end of the module of FIG. 12;

FIG. 15 is a view from one side of yet a further alternative embodiment;

FIG. 16 shows a further exemplary housing, incorporating anaccelerometer;

FIG. 17 shows how the accelerometer signal output is conditioned;

FIG. 18 shows the electronic circuitry associated with the embodiment ofFIG. 16;

FIG. 19 illustrates the operation of the algorithm used in the FIG. 16embodiment;

FIG. 20 shows another embodiment of the terminal of FIG. 1b; and

FIG. 21 shows a shock-protected electronic device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, as shown in FIG. 1, reference numeral 10generally identifies a hand-held scanner having a head 12 and anergonomically-shaped handle 14. A manually-operable trigger 16 issituated below the head 12 on an upper, forwardly-facing part of thehandle 14. As known from the above-identified patents incorporated byreference herein, a light source component, typically, but notnecessarily, a laser, is mounted inside the head 12. The light sourceemits a light beam along a transmission path which extends outwardlythrough a window 18 that faces indicia, e.g. bar code symbols, to beread. Also mounted within the head is a photodetector component, e.g. aphotodiode, having a field of view, and operative for collectingreflected light returning through the window 18 along a path from thesymbol.

A scanner component (to be described in more detail with reference toFIG. 2) is mounted within the head 12, and is operative for scanning thesymbol and/or the field of view of the photodetector. The scannercomponent includes at least one light reflector positioned in thetransmission path and/or the return path. The reflector is driven inoscillatory fashion by an electrically-operated drive, preferably at theresonant frequency of the scanner component, thereby producing ascanning light beam.

The photodetector generates an electrical analog signal indicative ofthe variable intensity of the reflected light. This analog signal isconverted into a digital signal by an analog-to-digital convertercircuit. This digital signal is conducted to a decode module (not shown)within the scanner. The decode module decodes the digital signal intodata descriptive of the symbol and the data are passed out along anexternal cable 20 to an external host device 24, normally a hostcomputer. Here the data are stored for further processing. Instead ofthe cable 20, the scanner 10 and the external host device 24 may be incommunication by a wireless connection, e.g., a radio link.

In operation, each time a user wishes to have a symbol read, the useraims the head at the symbol and pulls the trigger 16 to initiate readingof the symbol. The trigger 16 is an electrical switch that actuates thedrive means. The symbol is repetitively and rapidly scanned. As soon asthe symbol has been successfully decoded and read, the scanning actionis automatically terminated, thereby enabling the scanner to be directedto the next symbol to be read in its respective turn.

In addition, the head need not be a portable hand-held type, as fixedlymounted heads are also contemplated in this invention. Furthermore,scanners in accordance with the present invention may have manuallyoperated triggers, or may alternatively be continuously operated bydirect connection to an electrical source.

The oscillations need only last a second or so, since the multipleoscillations, rather than time, increase the probability of getting asuccessful decode for a symbol, even a poorly printed one. Theresonating reflector has a predetermined, predictable, known, generallyuniform, angular speed for increased system reliability.

Turning now to FIG. 1b, there is shown an alternative hand-held opticalscanner, this time taking the form of a scanning terminal 26. Theterminal comprises a hand-held case 28 having a data display screen 30and a data input keypad 32. A high speed scanning arrangement within thecase 28 produces a scanning light beam which extends outwardly through awindow 34 which faces the indicia to be read. Light reflected from theindicia passes back through the window 34 and impinges on aphotodetector component (not shown), for example a photodiode, whichcreates a returning light output signal. The information content withinthat signal may be stored in an on-board memory (not shown) or may bedownloaded to a remote computer via a data port 36. Alternatively, theinformation may be transmitted via a radio frequency signal produced byan on-board radio transmitter/receiver 38.

FIG. 2a shows an embodiment of a high speed scanning arrangementsuitable for use with either of the optical scanners of FIGS. 1a and 1b. The arrangement has a flexible beam 50, one end 53 of which isfixedly mounted by means of a screw 52 to a base support 54. The beam 50preferably comprises a generally planar leaf spring, which may be madeof Mylar(™), a plastics material, metal, or any other convenientflexible material. At the distal end 55 of the beam 50 is a mountingbracket 56,58 which is secured to the beam by means of a further screw60. Secured to one portion 56 of the mounting bracket is a generallyrectangular mirror (62) having a reflective mirror surface 64. Themirror extends downwardly from the distal end 55 of the beam 50,generally parallel with the length of the beam, towards the other end ofthe beam 53.

Mounted to the second portion 58 of the mounting bracket, on the otherside of the beam 50 from the mirror, is a permanent magnet 66. This ispositioned generally on an axis 68 of an electromagnetic coil 70, but ismounted perpendicular to the axis to save space.

In operation, the coil 70 is driven either with a pulsed electricalsignal, or an AC signal (eg. a sine-wave signal), thereby creating acontinuous or repetitive force on the magnet 66. The force repeatedlymoves the magnet into and out of the coil 70, thereby flexing the beam50 and causing oscillation of the mirror in the direction shown by thedouble-headed arrow 75. Alternatively, the force may be unidirectionalonly: for example a repeated pulse may draw the magnet into the coil,with the magnet moving in the other direction purely by virtue of theresilience of the beam 50. The perpendicular mounting of the magnet 66means that it does not protrude beyond the coil 70 when the beam 50bends to its fullest extent.

Preferably, the coil 70 is driven so that the scanning arrangementoscillates at a resonate frequency which is above the fundamental. Thepreferred mode of oscillation is a higher order mode, as is shownschematically in FIG. 2b. In this Figure, the dashed lines 50′ representthe rest position of the beam 50, and the solid lines represent one ofthe instantaneous positions of the beam during oscillation. For the sakeof clarity, the mirror and mounting bracket are omitted, and the amountof curvature is exaggerated. In this preferred embodiment, the beam iscaused to oscillate in such a way that there is a fixed node or axis 79approximately one third of the way along its length. The portion of thebeam 80 above this point bends as shown, as does the portion 82 betweenthe axis 79 and the base support 54: however, the node 79 remainssubstantially stationary. Other modes of oscillation, other than thefundamental, could also be used, depending upon the oscillationfrequency required. The exact frequency will of course depend upon thesize and mass of the components, but in the preferred embodiment thefrequency may for example be between 100 and 200 Hz; or it could begreater than 200 Hz.

By mounting the mirror 62 to the distal end 55 of the beam, andarranging for it to extend downwardly, parallel to the beam, the mirrorcenter of mass 72 may be brought close to the node 79. This allows forhigh speed scanning to take place without unduly stressing the beam 50.As will be appreciated, the mirror 62 is effectively oscillating about anominal rotation axis which is coincident with the node 79. Since themirror 62 and the magnet 66 are rigidly coupled together, they oscillateas one unit, which simplifies the drive signal control.

To further reduce stress on the beam 50, the mounting bracket 56,58 andthe permanent magnet 66 are both made relatively small and light incomparison with the mirror. The fact that the magnet is small, andpositioned far away from the nominal rotation axis 79, allows the coil70 to provide enough rotational moment for the start-up time to beextremely rapid (less than 50 milliseconds).

The relative lengths and masses of the beam 50 and the mirror 62 may beadjusted, as will be evident to the skilled man in the art, to providethe required frequency of oscillation. If necessary, additional weights74 may be secured to the mirror, thereby bringing the overall center ofmass 72 close to the nominal axis of rotation.

In alternative embodiments (not shown) the mirror 64 could be replacedwith any other suitable optical arrangement for diverting a light beam.For example, instead of the light beam being reflected from the mirrorsurface 62, it could instead be diverted by passing through a lens, aprism, a diffraction grating, or a holographic optical element. Also,the mirror 62 could be replaced with a solid state laser, the scanningmotion of the beam being caused by oscillation of the laser itself.

This last arrangement is shown schematically in FIG. 3, in which likeelements are given like reference numerals. In this embodiment, themirror 62 is replaced with a solid state laser 162 which is mounted tothe mounting bracket 56 by a rigid elongate support 164, extendinglongitudinally of the beam 50. The laser 162 includes beam-shapingoptics and a stop 166, and produces an output beam 163. In use, as thebeam 50 oscillates (as shown schematically in FIG. 2b) the laser 162also oscillates, thereby causing a scanning motion of the laser beam163. The scanning frequency may be high (for example between 100 and 200Hz) because of the close proximity of the nominal axis of rotation (thenode 79) and the center of mass 168 of the laser 162. Preferably, thesupport 164 is light but rigid so that it does not affect substantiallythe position of the center of mass of the support/laser assembly.

The embodiment of FIG. 3 may be used in combination with the embodimentof FIG. 2a, in optical series, to provide the capability of twodimensional scanning. Alternatively, the embodiment of FIG. 3 may beused in conjunction with any other known method of one dimensionalscanning.

Also, two high speed scanning arrangements of FIG. 2 may be usedtogether, in optical sequence, to create a beam which scans in more thanone direction. In that way, high speed multi-axis scan patterns may beproduced across the indicia to be read. Alternatively, the high speedscanning arrangement of FIG. 2 may be used in association with otherknown (one-dimensional) scanning arrangements to produce a similareffect.

In either arrangement, the drive signal applied to the coil 70preferably causes continued oscillation at the required frequency.Alternatively, however, a single pulse or drive signal could be appliedto the coil, simply starting the oscillation off, with the scan elementthen coming naturally to rest in a damped manner.

Either of the embodiments of FIGS. 2 or 3 may be manufactured as aself-contained scan module or element which may be mounted as a unitwithin any type of hand-held or fixed optical scanner, for example thoseshown in FIG. 1a or 1 b. In such a modular scanning arrangement, thebase support 54 may comprise part of the optical scanner casing, asshown for example at reference numeral 12 in FIG. 1a or referencenumeral 28 in FIG. 1b. In such an arrangement, the coil 70 may also bedirectly mounted to the casing (with the coil therefore not forming partof the replaceable module). Alternatively, the base support 54 of FIGS.2 and 3 may comprise a common mounting bracket to which is secured notonly the beam 50, but also the coil 70. In that arrangement, the coil 70forms part of the replaceable module, and is secured to the casing alongwith the other scanning components via the intermediary of the supportbracket 54.

FIGS. 4a and 4 b show respectively top and side views of a low costhousing within which the previously described scanning arrangements maybe incorporated.

The housing of FIG. 4 comprises a head portion 200 and amanually-graspable handle portion 202 having a trigger 204 which can beoperated by the user's finger. A scanning mechanism generally indicatedat 206 is located in the head portion, and provides a scanning laserbeam indicated by the dotted lines 208 which leaves the scanner via awindow 210.

The scanning mechanism 206 is surface-mounted to an elongate printedcircuit board (PCB) 212 which extends downwardly into the handle. Powerand/data transfer capabilities are provided via an external lead 214which couples to the PCB via a suitable power and/data transfer coupling216 at the lower end of the board. The trigger 204 has, within thehandle, an elongate metal tongue 218 which, when the trigger is pressed,applies force to an ON/OFF micro-switch 220 on the PCB.

The PCB may, in addition, include decode electronics 222 providing forin-housing decoding of bar code symbols or other indicia which are beingread by the scanner.

Preferably, all of the mechanical and/or electronic components withinthe housing, apart from those associated with the trigger 204 and thetongue 218, are surface mounted to the PCB. The PCB is then simplysecured to the housing by screws or other appropriate couplings 224,226.

Instead of or in addition to the data cable 214, the scanner may beprovided with a radio communications link 300. In such a case, power maybe provided not via an external lead but rather by an on-board batterypack 302.

In one preferred embodiment, the scanning mechanism 206 may be of thetype shown in FIG. 2a or of the type shown in FIG. 3. In an alternativeembodiment, the mechanism may be of the type now to be described withreference to FIG. 5a.

In FIG. 5a, the scanning mechanism 206′ includes a laser diode 230 thatproduces an outgoing laser beam which is reflected from a collectionmirror 232 onto an oscillating scanning mirror 234 to produce anoutgoing scanning beam 236. Light reflected from the indicia (not shown)being scanned impinges first on the scanning mirror 234, then on thecollection mirror 232 from which it is reflected to a photodiode orother photodetector 238. The photodetector produces an electrical outputsignal which travels via the PCB to the PCB electronics 222 (FIG. 4b).

The scanning mirror 234 is caused to oscillate back and forth about anaxis 240 by means of a drive signal applied to a coil 242. Thisinteracts with a magnet 244 on a rotating member 246 to which the mirror234 is also secured.

As best shown in FIG. 5b, the scanning mechanism is secured to the PCB212 by means of an angled mounting bracket 250. A flange 252 of themounting bracket is secured to the PCB by one or more screws 254.

An alternative module design is shown in FIGS. 12 to 14. In this design,a small optics module carries the mechanical and optical elements, withthe majority of the electronics being located elsewhere. In thepreferred embodiment, the optics module has an electrical connector forconnection to a printed circuit board (PCB) which carries the electroniccomponents such as the laser drive, the motor drive, the digitizer andthe decoder.

FIGS. 12 to 14 show an exemplary design in which the optics modulegenerally indicated at 950 comprises a variety of optical and mechanicalcomponents mounted to a base 952. Electrical connections 953 areprovided for coupling the module to a PCB 954.

On the module base 952 is mounted a semiconductor laser 962 the outputbeam 963 of which passes through a focusing lens 964 before beinginternally reflected by a prism 966. The beam then passes through anaperture 968 in a collector 970 before impinging upon an oscillatingscanning mirror 956 to provide an outgoing scanning laser beam 972. Thescanning mirror 956 is arranged to oscillate over an angle of about 28°by virtue of the interaction between a fixed magnet 958 and anelectromagnet coil 960. Light 974, reflected from the indicia, impingesback onto the scanning mirror 956 and onto the collector 970 whichfocuses it via an aperture 976 in a housing 978 to a photodetector 980.

Electrical connections, schematically illustrated at 953, 953′ and 953″,couple the optics module 950 to the PCB 954. The connections may includepower connections, ground connections, signal/control connections, anddrive connections for the coil 960 and the laser 962. Signal connectionsare also provided enabling the output from the photodetector 980 to bepassed to the PCB 954.

On the PCB 954 are mounted the electronic circuits 982 for operating theoptics module 950. These may include, for example, the laser driver, themotor drive, the digitizer and the decoder.

Such an arrangement provides for an efficient and convenientmanufacturing operation.

An alternative optics module is shown schematically in FIG. 15. In thisarrangement, outgoing laser light from a semiconductor laser 600 passesthrough a focusing lens 602, an aperture 604 in a collecting mirror 606and impinges upon the scanning mirror 608 to form an outgoing scanningbeam 610. The scanning mirror 608 is mounted on a Mylar strip 612, andis caused to oscillate by virtue of the interaction between a permanentmagnet 614 and an electromagnetic driving coil 616.

Reflected light 618 from the indicia (not shown) being read firstimpinges once more onto the scanning mirror 608, and is then focused bymeans of the concave collection mirror 606 onto a filter 620 andphotodetector 622 assembly.

The optical elements are mounted to a base 624 which carries anelectrical connector 626 via which electrical signals can be transferredto and from the module. In particular, the connector 626 may carrypower, ground lines, control signals, drive signals for the coil 616 and(via the additional coupling 628) for the laser 600. In addition, theconnector 626 may include data lines for transferring from the moduledata signals representative of light received by the photodetector 622.

The base 624 may further include one or more application-specificintegrated circuits 630.

In the embodiments of FIGS. 12 and 15, the modules may optionallyinclude some or all of the required electronic components such as adigitizer and/or a decoder. In such a case, the module is self-containedand simply plugs into a generic PCB. The generic PCB then need not carrydecode or digitizing circuitry.

In any of the preceding embodiments, the data and/or other connectionsmay be made by way of a standard PCMCIA card connector, if desired. Forexample, in the embodiment of FIG. 4b, the data lead 214 may be coupledto the PCB 212 via a PCMCIA card-type connector. Alternatively, theradio frequency transmitter 300 may also be coupled via this type ofconnector.

Where a PCMCIA card connector is used, the preferred arrangement is asshown in FIG. 6. In order to prevent radio frequency leakage from aPCMCIA package, the plastic PCMCIA connector is selectively coated withan appropriate conductive material such as silver, copper, nickel orgold ink or paint. Other conductive coatings could of course beenvisaged such as, for example, the coating supplied by Acheson ColloidsCompany of Ontario, Canada, under product reference Electrodag 18DB70.

The coating covers the upper surface 410 of the connector, the lowersurface 412 and the front surface 414. The coating at least partiallycontinues inside some of the cavities, to make an electrical connectionbetween the exterior coating and ground. According to the PCMCIAstandard, socket positions 1, 34, 35 and 68 are grounded and the coatingmay extend into, and make electrical contact with ground within, any orall of these sockets.

In addition, coating is provided within the other contact loadpositions, but no electrical connection is made to the grounded exteriorshell coating.

The electrically conductive coating is, in addition, in electricalcontact with the PCMCIA top and bottom covers (not shown).

When used with a standard metal card frame assembly, this embodimentensures substantial sealing of RF leakage out of the PCMCIA assembly.

The embodiment of FIGS. 4a and 4 b may include an abuse-detectorgenerally indicated by reference numeral 700, and illustrated in moredetail in FIGS. 7 and 8 to which reference should now be made.

The abuse detector 700 comprises a molded plastics material ring 702,having inwardly-directed spokes 704 which support a central weight 706.The ring 702, the spokes 704 and the weight 706 may be all of one piece,as is illustrated in FIG. 8 which is a longitudinal cross-section alongthe central line of one of the spokes. Each spoke 704 is coated with astress-sensitive coating 708. The unit is secured to a suitable supportwithin the scanner, for example the PCB 212 in FIG. 4b, by means of anannular adhesive coating 710 applied to one side of the ring 702.

The coating 708 is chosen so that it visibly cracks when the equipmentis subjected to a level of acceleration that exceeds the specifiedlimits of use(e.g., 2000 g). This occurs by the twisting or longitudinalbending of the spokes 704 as the weight 706 moves slightly with respectto the ring 702. It will be noted from FIG. 8 that in the preferredembodiment the weight 706 is spaced slightly forwardly of the PCB, byvirtue of a rearwardly-extending annular boss on the ring 702, therebyenabling the weight to move freely as the spokes bend and/or twist.

In an alternative embodiment (not shown) the ring 702 may be secured toa circular base, which may itself be attached, for example by means ofan adhesive, to the PCB 212.

An abuse meter of the type illustrated in FIGS. 7 and 8 may be appliedto any type of hand-held equipment, not only bar code readers. It mayhave particular application to hand-held computer terminals and likeequipment which may, in a busy industrial or commercial environment, beliable to sustain accidental shocks.

A rather more sophisticated approach to the problems of unexpected shockis illustrated in FIGS. 9 to 11. This proceeds from the recognition thatalthough sudden shock, due for example to banging or dropping thedevice, may not cause permanent damage, it can cause interruption of theoperation of the electrical process/software within. Such electronicinterruptions may cause data and/or software program loss that may notbe easily recoverable. Accordingly, the embodiment of FIG. 4b includesan accelerometer with associated circuitry 800 for sensing suddenacceleration of the device and for automatically causing the computer topause or to shut down the current process before the possible shockcauses loss of data and/or disruption of that process. A suitableaccelerometer for use in all types of hand-held or portable computerperipherals is the Model 3031 accelerometer supplied by IC Sensors ofMilpitas, Calif.

In operation, the accelerometer is designed to detect suddenaccelerations, for example that caused when the device is dropped, andto alert the central processing unit (CPU) accordingly. The computer istherefore warned of a possible imminent shock, allowing all currentprocessing to be frozen and for the electronics to be shut down beforethe shock occurs. At the time of the shock, no processing will be inprogress, and hence no electronic information will be lost due to theshock. Of course, this does not preclude loss of capability of thedevice due to actual physical damage.

Upon indication that the device is accelerating, the CPU is arranged toenter a low-power “pause” mode in which the current processes, and thestatus conditions, are saved. After the impact, the user may reactivatethe system and can continue the processing, from the point at which itwas shut down, without loss of data.

Shock prediction may also be used to protect physical components fromdamage due to a sudden shock. Once the computer has been warned of thehigh acceleration rate, it may actuate electro-mechanical devices toprovide additional mechanical protection. For example, a miniature diskdrive can be locked before impact to provide additional protection tothe drive head and platters.

It will be understood that acceleration-detection in three dimensionswill typically be preferred, since the impact may occur at any angle.However, one-dimensional acceleration sensing could suffice if, in aparticular application, protection from shock is needed only in aparticular direction.

FIG. 9 shows the alerting algorithm in more detail. Starting at 910,acceleration of the device is continually monitored at 912 by theaccelerometer 800 (FIG. 4b). When the accelerometer determines at step914 that a threshold is exceeded, an alert is sent at 916 to the CPU,for appropriate action to be taken. The accelerometer then continues tomonitor the acceleration level, so that it can signal a return to normalconditions. If the limit was not exceeded at step 914, monitoring simplycontinues.

FIG. 10 shows the flow of the CPU response to an acceleration alert.Starting at 920, the CPU first, at step 922, sends a message to actuateany electro-mechanical locking devices to prepare for the shock. At 924the CPU then stops all current running programs, and saves the statusinformation of those processes. Finally, at 926, the CPU puts thecomputer into a power-down or “sleep” mode.

The recovery from a power-down event caused by an acceleration alert isillustrated schematically in FIG. 11. Starting at 930, when the userwakes up the unit (via a keystroke or other input), the CPU then checksat 932 to see whether the power-down mode it is coming out of was due toan acceleration alert. If not, control then passes at 933 to the normalwake-up routine.

If the power-down was caused by an acceleration alert, the CPU informsthe user at 934 that it experienced an acceleration shutdown. The systemthen asks whether the user wishes to continue the application from thepoint at which it was paused. The user's input is checked at 936, and ifthe user has decided not to continue from the point at which the processwas paused, a top level routine 937 may then be initiated. On the otherhand, if the user does decide to continue the application from thepaused point, the electro-mechanical locks are removed at 938, and at940 the process status information is re-installed and the applicationcontinued from the appropriate point.

An alternative and yet more sophisticated approach is illustrated inFIGS. 16 to 19. FIG. 16 shows a hand-held scanner body 1610 having ahead portion 1620 and a manually-graspable handle portion 1630. Theinternal scanning components (not shown) are actuated by means of adigitally-operated trigger 1640.

Mounted within the handle 1630 is a printed circuit board 1650 which iscoupled by means of a flexible electrical connection 1660 to x, y and zaccelerometers 1670, fixedly secured to the housing.

The PCB 1650 mounts electronic components, shown in FIGS. 17 and 18, forprocessing the signals received from the accelerometers 1670.

FIG. 17 illustrates the signal processing for the x-channel. Anacceleration a_(x) applied to the accelerometer 1670 x produces a rawoutput signal 1708 x on the accelerometer output 1710 x. This signal isapplied to an x-filter 1712 x which produces a smoothed output 1714 x onthe filter output 1716 x. The y and z channels are identical.

The three channels already described in connection with FIG. 17, may beseen on the left-hand side of FIG. 18. As shown in that drawing, thefilter output for each channel is applied to one input of a comparator1802. The other input, in each case, is a fixed voltage 1804representative of an acceleration of 200 g. The respective comparatoroutputs 1806 are then applied to three respective inputs of a centralOR-gate 1810. This accordingly creates a wake-up signal on an output1812 when any one or more of the comparators 1804 have registered anacceleration in excess of 200 g. The wake-up signal on the line 1812 isplaced on a bus 1814 which supplies the information respectively to x, yand z microprocessors 1816. Analog signals are also supplied to therespective microprocessors from the output of the x, y and z filters1712. Each microprocessor has associated with it a corresponding memory1818. The memories are coupled with a further bus 1820 to a commonoutput port or data coupling 1822, whereby the information in thememories 1818 may be downloaded to a fixed central computer (not shown).

In operation, the individual outputs of the accelerometers areconstantly monitored, and a “wake-up” signal is supplied on the line1812 if any one or more of the accelerometers records an acceleration ofgreater than 200 g. In that event, data representative of the filteroutputs are supplied to the respective microprocessors, and may bestored in the memories for further study or processing. The precisewaveform which has triggered the “wake-up” signal on the line 1812 maystill be recovered and stored in memory by virtue of its having beendelayed in transit by a delay element 1824. The respective x, y and zdelay elements may comprise standard delay lines, or may, morepreferably, comprise EEPROMs, arranged to store the incoming signals ona temporary basis, and to pass them on if and only if a “wake-up” signalis generated. For example, each EEPROM may store waveforms relating tothe most recent five second period, with previous time periods beingconstantly overwritten unless and until a “wake-up” signal is generated,in which case the waveforms are passed on to the microprocessors 1816.In an alternative embodiment (not shown) the EEPROMs may comprise partof the respective microprocessors 1816.

In a further development of the idea, additional sensors 1826 may beprovided, for each channel, to supply additional information that may beuseful to assist in the analysis of the waveforms. For example, it mayunder some circumstances be advantageous to retain information relatingto the raw (pre-filtered) signals, and/or the x, y, z attitude of theequipment, over a period of time.

In addition, or alternatively, a further channel (not shown) may beprovided for the storage of additional information such as the ambienttemperature, the temperature of the laser diode, the on/off state of thescanner, the frequency/duration of use, or the state of variouselectronic or mechanical components. With this additional information,the device effectively acts as a “black-box” for an optical scanner, orother electronic equipment, allowing the manufacturer or other testingpersonnel access to a complete device log. If a user reports that aparticular scanner has stopped working, or has developed a malfunction,it is then an easy matter to download the log via the connector 1822,and to investigate the device's recent history. It may for example maybecome evident from the log that the device has been subject to abusivetreatment which has not been reported by the user.

Turning now to FIG. 19, there is shown a preferred mode of operation,which differs slightly from that already discussed in connection withFIG. 18, in that the entire waveform is loaded into memory only if adeceleration of greater than 500 g has been detected; if the detecteddeceleration is between 200 and 500 g, the system simply makes a note ofthat fact.

At step 1910, the algorithm is launched as the scanner is powered up. Ifthe user wishes to upload the information stored in the memories, herequests an upload at step 1914, and the upload is effected at 1916. Inthis diagram, “EE” represents an erasable EPROM.

If an upload has not been requested, the system goes into a suspendedmode at 1918. It remains in that mode until a “wake-up” signal issupplied at 1920, this telling the system that at least oneaccelerometer has detected a deceleration of greater than 200 g (comparethe “wake-up” signal on the line 1812 of FIG. 18).

At step 1922, an A/D converter is initialized, the correspondingwaveform sampled at 100 sampling points, and the digital values storedin RAM. A check is then made at 1924 to see whether any of these samplesare representative of decelerations greater than 500 g. If not, thencontrol passes to box 1926. The current value of the counterrepresenting decelerations of between 200 and 500 g is read, the valueis incremented, and the new value is then stored in EE. Control thenpasses back to box 1918, to await a further “wake-up” signal.

If any samples of greater than 500 g are found at step 1924, controlpasses the box 1928. The entire digitized sample is then stored in EE,and the pointers updated, allowing the waveform to be reconstructed at alater stage. Other relevant information may then be stored, at 1930,such as for example the temperature. Control then returns to box 1918and further activity is suspended until another “wake-up” signal isdetected.

It will of course be appreciated that the equipment and processesdescribed above, and illustrated in FIGS. 9 to 11 and 16 to 19 may findapplication in many types of portable equipment, not only bar codereaders. Other applications include portable hand-held and notebookcomputers, computer terminals and other electronic equipment.

FIG. 20 depicts a terminal analogous to the one shown in FIG. 1b in thatit has a display 30 and a keypad 32. However, the window is not locatedat the front, but instead a window 210 is located on a bottom wall 211.The scan module or engine 206 is mounted on the PCB 212 such that theoutgoing laser scan beam exits the housing at an acute angle on theorder of 30° relative to the horizontal. The scan beam is notperpendicular or parallel to any outer wall of the terminal, or to thePCB 212.

Since hand-held electronic devices are subject to a considerable amountof mechanical stress due to dropping to hard surfaces, etc., it isimportant that the housing be designed in a durable manner. Anotherfeature of the present invention, as shown in FIG. 21, is to provide anexternal housing of a hand-held device such as a lap top computer, a barcode reaader, etc., comprised of three distinct sections or components,namely an upper housing 11, a middle housing 13, and a lower housing 15,although such sections may be any three (or more) segments or regions ofthe housing. The upper housing and the lower housing are made of arelatively rigid thermoplastic such as ABS/IPC while the middle housingwhich separates the upper housing and lower housing, is preferably madefrom a “semi-rigid” thermoplastic elastometer such as Texin® (Texin® isa trademark of Miles Inc., of Pittsburgh, Pa., relating to a family ofurathane thermo plastic materials). We use the term “semi-rigid” todescribe Texin as a material that is a cross between an elastometer,with the properties of high strain and low set and a standardthermoplastic, with the properties of high rigidity and brittleness.

The shape and design of the housing is such that the middle housing isthe first point of contact on a side load that might typically occurwhen the reader is dropped. This portion of the housing, when made fromTexin, is capable of sustaining relatively large strains withoutexperiencing permanent deformation. The large deflection serves togradually slow down the impact against sensitive internal components,hence, reducing the shock load, much the same way that an internal shockmounting system such as rubber bumpers, would.

The housing can easily be designed to allow the energy absorbentproperties of the middle housing to work for a load directed onto theupper housing and a soft boot or “foot” typical of the handle portion ofa gun-shaped bar code reader, would be needed for a bottom load. Anotherimportant difference in this design is that the optical assembly can berigidly mounted to the lower housing for accurate mechanicalregistration. This reduces the likelihood of the common problem ofalignment of a “soft mounted” or suspending optical assembly to thehousing. An additional benefit is the fact that the Texin® material hasenough compressibility to provide a moisture and dust proof seal whenfastened snugly to the other portions of the housing. Thus, if sealingis desired, the need for a separate gasket is eliminated.

It will be understood that each of the elements described above, or twoor more together, may also find useful applications in other types ofconstructions which differ from those specifically desccribed above.Elements described in connection with one embodiment may, wherecompatible, be combined with those described in connection with anotherembodiment.

While the invention has been illustrated and described as embodied in ahigh speed scanning arrangement, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit or scope of thepresent invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of the appendedclaims.

We claim:
 1. An optical scanning assembly in an electro-optical systemfor reading indicia having parts of different light reflectivity, theassembly comprising: a) a printed circuit board carrying electricalcircuitry and board connectors; and b) a plug-in scan module including asource for directing a light beam at an indicium to be read, a detectorhaving a field of view for detecting light reflected off the indiciumand for generating a data signal corresponding to the indicium, and ascanner for scanning at least one of the light beam and the field ofview, the source, the detector and the scanner being supported by thescan module for joint movement, the scan module including moduleconnectors plugged into the board connectors during reading forconducting electrical signals between the electrical circuitry on theboard and the scan module.
 2. The optical scanning assembly according toclaim 1, wherein the scan module has a base on which the source, thedetector and the scanner are mounted.
 3. The optical scanning assemblyaccording to claim 2, wherein the base is generally planar, and whereinthe board is generally planar, and wherein the base and the board engageeach other in surface area contact.
 4. The optical scanning assemblyaccording to claim 2, wherein the module connectors are pins, andwherein the board connectors are sockets into which the pins areinserted.
 5. The optical scanning assembly according to claim 1, whereinthe source is a semiconductor laser.
 6. The optical scanning assemblyaccording to claim 1, wherein the scan module includes an optical trainfor focusing the light beam.
 7. The optical scanning assembly accordingto claim 1, wherein the detector is a photodiode.
 8. The opticalscanning assembly according to claim 1, wherein the scanner includes anoscillatable scan mirror for reflecting the light beam from the sourceto the indicium, and an electro-magnetic drive for oscillating the scanmirror to sweep the light beam across the indicium.
 9. The opticalscanning assembly according to claim 8, wherein the scan mirror iscantilever mounted on a flexure, and wherein the drive includes apermanent magnet mounted to the scan mirror for joint movementtherewith, and a coil for interacting with the magnet to flex theflexure and move the scan mirror.
 10. The optical scanning assemblyaccording to claim 9, wherein the flexure is a planar spring.
 11. Theoptical scanning assembly according to claim 1, wherein the electricalcircuitry on the board includes a power supply for supplying electricalpower to the source, the detector and the scanner.
 12. The opticalscanning assembly according to claim 1, wherein the electrical circuitryon the board includes a signal processor for processing the data signalinto data descriptive of the indicium.